target-sh4: Add support for ldc & stc with sgr

Add support for the following missing priviledged intructions:

For SH4:
- stc sgr, Rn
- stc.l sgr, @-Rn

For SH4A:
- ldc Rm, sgr
- ldc.l @Rm+, sgr
Signed-off-by: NAlexandre Courbot <gnurou@gmail.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target-sh4/translate.c

@@ -1543,6 +1543,8 @@ static void _decode_opc(DisasContext * ctx)
 	LDST(vbr,  0x402e, 0x4027, 0x0022, 0x4023, CHECK_PRIVILEGED)
 	LDST(ssr,  0x403e, 0x4037, 0x0032, 0x4033, CHECK_PRIVILEGED)
 	LDST(spc,  0x404e, 0x4047, 0x0042, 0x4043, CHECK_PRIVILEGED)
+	ST(sgr,  0x003a, 0x4032, CHECK_PRIVILEGED)
+	LD(sgr,  0x403a, 0x4036, CHECK_PRIVILEGED if (!(ctx->features & SH_FEATURE_SH4A)) break;)
 	LDST(dbr,  0x40fa, 0x40f6, 0x00fa, 0x40f2, CHECK_PRIVILEGED)
 	LDST(mach, 0x400a, 0x4006, 0x000a, 0x4002, {})
 	LDST(macl, 0x401a, 0x4016, 0x001a, 0x4012, {})